1. Field of the Invention
This specification relates to a GaN Heterojunction Field Effect Transistor (HFET) device with a FexNy layer (or interlayer), and a fabricating method thereof.
2. Background of the Invention
A nitride semiconductor exhibits several advantages including high threshold electric field, low On-resistance, high temperature, and high frequency applications. The spotlight to the nitride semiconductor comes from those advantages, and advanced research on nitride semiconductor as a material for the next generation semiconductor device is conducted.
In recent time, mainstream high power devices include MOSFET and IGBT, and also devices such as GaN-based HEMT, HFET, MOSFET and the like are studied.
The HEMT which uses high electron mobility is employed for communication devices exhibiting high frequency performance.
Also, the HEMT is used in power semiconductors, communication devices showing high frequency performance, and the like. In recent time, developments of hybrid/fuel cell cars are ongoing, and various overseas corporations are launching hybrid vehicles. Reliable operations at high temperature are required for semiconductor switches, which are disposed within the voltage booster converter and inverter for connecting a motor to a generator within a hybrid vehicle, due to heat generated from an engine. Gallium nitride (GaN) may allow for reliable operation at the high temperature owing to its wide bandgap, and is suitable for the next generation semiconductor switch within hybrid cars.
FIG. 1 is an exemplary view showing a general structure of Heterojunction Field Effect Transistor (HFET).
As shown in FIG. 1, a general HFET 10 may switch a 2 DEG current which, flows from a drain electrode to a source electrode, through a schottky gate electrode.
The general HFET 10 may include a substrate (not shown), a first GaN layer 11 formed on the substrate, an AlGaN layer 12 on the first GaN layer 11, a second GaN layer 13 on the AlGaN layer 12, a gate electrode 14, a source electrode 15 and a drain electrode 16 formed on the second GaN layer 13.
For the general HFET device 10, quality of the schottky characteristic using gate operations may have a great influence on a switch characteristic of the device.
Therefore, a technology for reducing a leakage current of the HFET and maximizing a breakdown voltage is needed.